This invention relates to a case packer, or an apparatus for sequentially depositing articles such as packaged products inside a case, or a container such as a cardboard box.
Products such as potato chips, already weighed and sealed in bags by means of a bag maker-packaging machine, are shipped to the market in containers such as cardboard boxes, each containing a specified number of these bags. Japanese Patent Publication Tokkai 6-263106, for example, disclosed a case packer which may be used for such a purpose, using conveyors to sequentially transport packaged products supplied from a bag maker-packaging machine and a packing mechanism for automatically arranging these packaged products inside a given container such as a cardboard box.
The aforementioned packing mechanism may comprise a holder member which is freely movable between a starting position above where the packaged products are brought in and a delivery position above where the container is placed to be filled, having a suction pad on its lower surface for sucking up and releasing products. If such a holder member is moved back and forth between its starting and delivery positions and lowered and raised at each of these positions, each packaged product brought in by the conveyor can be picked up from above by the suction pad and lowered into and deposited inside the container.
For a reason of economy, for example, it is often desirable to put as many packaged products as possible in a container by overlapping the side edges of mutually adjacent packages inside the container. FIG. 23 will be referenced next to explain how this is usually done.
As shown in FIG. 23, packaged products X are sequentially transported by a first belt 501, say, from a bag maker-packaging machine and dropped onto the upstream end of a second conveyor belt 502 to be further transported in the downstream direction indicated by arrow A. Each time a product X is dropped onto the upstream end of the second conveyor belt 502, the second conveyor belt 502 is advanced by a distance n which is shorter than the length of the (bag of the) product X by m (the overlapping length). After this process of intermittent motion is repeated for a specified number (four, in the example) of times, this specified number of products X are now aligned in a sequentially overlapping relationship in the direction of motion A. The second conveyor belt 502 is thereafter advanced in a continuous motion, sending off the aligned products x all at once onto a third conveyor belt 503 such that this group of products X can be captured together by the suction pad of the packing mechanism as they remain overlapped.
As soon as one such group of products X is transported over to the third conveyor belt 503, the mode of operation of the second conveyor belt 502 is switched from continuous to intermittent, beginning to receive another group of packaged products X from the first conveyor belt 501.
In this cycle of operations, the first conveyor belt 501 must be temporarily stopped as soon as the aforementioned continuous motion of the second conveyor belt 502 is started and made to wait until the group of products X then on the second conveyor belt 502 is completely transported over to the third conveyor belt 503 by advancing it by a distance indicated by letter L in FIG. 23. It is because, if the first conveyor belt 501 were not stopped and the next product X were allowed to drop onto the continuously moving second conveyor belt 502, this product X would advance farther than its length, and the following product X to be dropped from the first conveyor belt 501 would not be able to overlap properly with the preceding one. Thus, not only the first conveyer belt 501 but all processes which are being carried out on the upstream side of it must also be stopped temporarily and wait. This would delay the entire packing operation of the system as a whole.
With a packing mechanism as described above, furthermore, the holder member cannot be moved too fast back and forth between the starting position and the delivery position. Because only one group of products can be transported from the starting position to the delivery position as the holder member makes one cycle of its reciprocating motion, prior art packing mechanisms of this type are not sufficiently efficient. Moreover, the suction pad is not always successful in sucking up all of a group of products intended to be sucked up at any one time. If one or more of them fail to be picked up, or if all of them are picked up but some of them are not properly positioned when they are lifted up, the specified number of products may not be successfully deposited in the container or they may not be properly aligned inside the container as intended.